The World Health Organization said the Israeli military attacked its staff residence and main warehouse in the Gazan city of Deir al-Balah, compromising its operations in Gaza.

The United Nations agency said the WHO staff residence was attacked three times on Monday, with airstrikes causing a fire and extensive damage, and endangering staff and their families, including children.

Israeli tanks pushed into southern and eastern districts of Deir al-Balah for the first time on Monday, an area where Israeli sources said the military believes hostages may be held. Tank shelling in the area hit houses and mosques, killing at least three Palestinians and wounding several others, local medics said.

"Israeli military entered the premises, forcing women and children to evacuate on foot towards Al-Mawasi amid active conflict," WHO said.

"Male staff and family members were handcuffed, stripped, interrogated on the spot, and screened at gunpoint."

Two WHO staff and two family members were detained, it said in a post on X, adding that three of them were later released.

"WHO demands the immediate release of the detained staff and protection of all its staff," WHO director-general Tedros Adhanom Ghebreyesus said.

Deir al-Balah is packed with Palestinians displaced during more than 21 months of war in Gaza, hundreds of whom fled west or south after Israel issued an evacuation order, saying it sought to destroy infrastructure and capabilities of the militant group Hamas.

WHO said its main warehouse, located within an evacuation zone, was damaged on Sunday due to an attack that triggered explosions and a fire inside.

WHO stated it will remain in Deir al-Balah and expand its operations despite the attacks.

Britain and more than 20 other countries called on Monday for an immediate end to the war in Gaza and criticised the Israeli government's aid delivery model after hundreds of Palestinians were killed near sites distributing food. (Reuters)